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            ZYNQ学习笔记-IIC驱动的开发
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    <a class="article-tag-none-link" href="/tags/IIC/" rel="tag">IIC</a>, <a class="article-tag-none-link" href="/tags/Linux/" rel="tag">Linux</a>, <a class="article-tag-none-link" href="/tags/ZYNQ/" rel="tag">ZYNQ</a>
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            <h1 id="ZYNQ学习笔记-IIC驱动的开发"><a href="#ZYNQ学习笔记-IIC驱动的开发" class="headerlink" title="ZYNQ学习笔记-IIC驱动的开发"></a>ZYNQ学习笔记-IIC驱动的开发</h1><p>linux中有着一个IIC子系统，为IIC设备驱动提供了抽象IIC接口。IIC与硬件相关的底层驱动由芯片厂商进行适配，普通用户只需要关注上层的抽象层即可完成驱动开发。</p>
<span id="more"></span>

<h2 id="Linux中IIC设备的重要概念"><a href="#Linux中IIC设备的重要概念" class="headerlink" title="Linux中IIC设备的重要概念"></a>Linux中IIC设备的重要概念</h2><p>关于IIC子系统，有几个重要的概念需要掌握。首先看一下IIC子系统的框图：<br><img src="https://s21.ax1x.com/2024/08/10/pASR311.png" alt="image-20240416195931949"></p>
<ul>
<li>I2C核心：提供抽象层代码的核心。</li>
<li>I2C总线驱动：提供I2C通信能力。</li>
<li>I2C设备驱动：提供设备的注册和设备驱动的注册。</li>
</ul>
<p>对于用户来说，需要弄明白以下几个数据结构(均定义在<code>include/linux/i2c.h</code> 中)：</p>
<ul>
<li>i2c_adapter结构体:对应I2C外设的抽象层，每个代表一个外设。</li>
<li>i2c_algorithm结构体:对应I2C的传输方法，包含在i2c_adapter中，传输具体数据时调用的函数方法。</li>
</ul>
<p>上面两者的具体实现方法由芯片公司提供的I2C总线驱动实现，普通用户无需知道细节。对普通用户来说，需要重点关注以下几个数据结构;</p>
<ul>
<li>i2c_client结构体:</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">i2c_client</span> {</span></span><br><span class="line"> <span class="type">unsigned</span> <span class="type">short</span> flags; <span class="comment">// 标志</span></span><br><span class="line"> <span class="type">unsigned</span> <span class="type">short</span> addr; <span class="comment">// 芯片地址， 7 位，存在低 7 位</span></span><br><span class="line"></span><br><span class="line"> <span class="type">char</span> name[I2C_NAME_SIZE]; <span class="comment">// 设备名字</span></span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_adapter</span> *<span class="title">adapter</span>;</span> <span class="comment">// 对应的 I2C 适配器</span></span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">device</span> <span class="title">dev</span>;</span> <span class="comment">// 内置 device 结构体</span></span><br><span class="line"> <span class="type">int</span> irq; <span class="comment">// 中断</span></span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">list_head</span> <span class="title">detected</span>;</span></span><br><span class="line"> <span class="meta">#<span class="keyword">if</span> IS_ENABLED(CONFIG_I2C_SLAVE)</span></span><br><span class="line"> <span class="type">i2c_slave_cb_t</span> slave_cb; <span class="comment">/* callback for slave mode */</span></span><br><span class="line"> <span class="meta">#<span class="keyword">endif</span></span></span><br><span class="line">}</span><br></pre></td></tr></table></figure>

<p>一个I2C总线下的从设备对应一个i2c_client结构体变量。当驱动每匹配上一个设备时(通过设备树的compatible与of表匹配或者无设备树的i2c_device_id的name与I2C设备名字是否相同)，系统就会分配一个client。</p>
<ul>
<li>i2c_driver结构体:</li>
</ul>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">i2c_driver</span> {</span></span><br><span class="line"> <span class="type">unsigned</span> <span class="type">int</span> <span class="class"><span class="keyword">class</span>;</span></span><br><span class="line"></span><br><span class="line"> <span class="comment">/* Notifies the driver that a new bus has appeared. You should avoid</span></span><br><span class="line"><span class="comment"> * using this, it will be removed in a near future.</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"> <span class="type">int</span> (*attach_adapter)(<span class="keyword">struct</span> i2c_adapter *) __deprecated;</span><br><span class="line"></span><br><span class="line"> <span class="comment">/* Standard driver model interfaces */</span></span><br><span class="line"> <span class="type">int</span> (*probe)(<span class="keyword">struct</span> i2c_client *, <span class="type">const</span> <span class="keyword">struct</span> i2c_device_id *);</span><br><span class="line"> <span class="type">int</span> (*remove)(<span class="keyword">struct</span> i2c_client *);</span><br><span class="line"></span><br><span class="line"> <span class="comment">/* New driver model interface to aid the seamless removal of the</span></span><br><span class="line"><span class="comment"> * current probe()'s, more commonly unused than used second parameter.</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"> <span class="type">int</span> (*probe_new)(<span class="keyword">struct</span> i2c_client *);</span><br><span class="line"></span><br><span class="line"> <span class="comment">/* driver model interfaces that don't relate to enumeration */</span></span><br><span class="line"> <span class="type">void</span> (*shutdown)(<span class="keyword">struct</span> i2c_client *);</span><br><span class="line"></span><br><span class="line"> <span class="comment">/* Alert callback, for example for the SMBus alert protocol.</span></span><br><span class="line"><span class="comment"> * The format and meaning of the data value depends on the protocol.</span></span><br><span class="line"><span class="comment"> * For the SMBus alert protocol, there is a single bit of data passed</span></span><br><span class="line"><span class="comment"> * as the alert response's low bit ("event flag").</span></span><br><span class="line"><span class="comment"> * For the SMBus Host Notify protocol, the data corresponds to the</span></span><br><span class="line"><span class="comment"> * 16-bit payload data reported by the slave device acting as master.</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"> <span class="type">void</span> (*alert)(<span class="keyword">struct</span> i2c_client *, <span class="keyword">enum</span> i2c_alert_protocol protocol,</span><br><span class="line"> <span class="type">unsigned</span> <span class="type">int</span> data);</span><br><span class="line"></span><br><span class="line"> <span class="comment">/* a ioctl like command that can be used to perform specific functions</span></span><br><span class="line"><span class="comment"> * with the device.</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"> <span class="type">int</span> (*command)(<span class="keyword">struct</span> i2c_client *client, <span class="type">unsigned</span> <span class="type">int</span> cmd, <span class="type">void</span> *arg);</span><br><span class="line"></span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">device_driver</span> <span class="title">driver</span>;</span></span><br><span class="line"> <span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_device_id</span> *<span class="title">id_table</span>;</span></span><br><span class="line"></span><br><span class="line"> <span class="comment">/* Device detection callback for automatic device creation */</span></span><br><span class="line"> <span class="type">int</span> (*detect)(<span class="keyword">struct</span> i2c_client *, <span class="keyword">struct</span> i2c_board_info *);</span><br><span class="line"> <span class="type">const</span> <span class="type">unsigned</span> <span class="type">short</span> *address_list;</span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">list_head</span> <span class="title">clients</span>;</span></span><br><span class="line"></span><br><span class="line"> <span class="type">bool</span> disable_i2c_core_irq_mapping;</span><br><span class="line">};</span><br></pre></td></tr></table></figure>

<p>这个结构体中，需要注意几个成员：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* Standard driver model interfaces */</span></span><br><span class="line"><span class="type">int</span> (*probe)(<span class="keyword">struct</span> i2c_client *, <span class="type">const</span> <span class="keyword">struct</span> i2c_device_id *);</span><br><span class="line"><span class="type">int</span> (*remove)(<span class="keyword">struct</span> i2c_client *);</span><br></pre></td></tr></table></figure>

<p>probe函数在设备匹配成功后会执行，每次匹配得到一个i2c_client。</p>
<p>remove函数在注销设备时使用，要注销的设备通过i2c_client传入。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">device_driver</span> <span class="title">driver</span>;</span></span><br><span class="line"><span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_device_id</span> *<span class="title">id_table</span>;</span></span><br></pre></td></tr></table></figure>

<p>两个成员设计IIC设备的匹配。传统匹配使用i2c_device_id表进行，使用设备树则用device_driver中的of_match_table 成员变量匹配compatible。</p>
<p>IIC驱动的单位是driver，IIC驱动加载时需要调用函数：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">int</span> <span class="title function_">i2c_register_driver</span><span class="params">(<span class="keyword">struct</span> module *owner,<span class="keyword">struct</span> i2c_driver *driver)</span></span><br></pre></td></tr></table></figure>

<p>owner一般为<code>THIS_MODULE</code>。</p>
<p>与该函数对应有个宏帮助传递owner参数：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">define</span> i2c_add_driver(driver) \</span></span><br><span class="line"><span class="meta"> i2c_register_driver(THIS_MODULE, driver)</span></span><br></pre></td></tr></table></figure>

<p>卸载驱动时需要调用注销：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">void</span> <span class="title function_">i2c_del_driver</span><span class="params">(<span class="keyword">struct</span> i2c_driver *driver)</span></span><br></pre></td></tr></table></figure>

<p><strong>IIC驱动的单位是driver</strong>，这句话理解为，一个driver对应多个client，即一个驱动可以驱动多个同类型设备(基于匹配表)。<strong>每匹配到一个client，都需要在probe把字符设备创建过程跑一遍，在remove把注销过程跑一遍</strong>。</p>
<h2 id="一般的驱动注册结构"><a href="#一般的驱动注册结构" class="headerlink" title="一般的驱动注册结构"></a>一般的驱动注册结构</h2><p>对于一般用户，需要注册i2c_driver，一般的注册结构如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* i2c 驱动的 probe 函数 */</span></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">xxx_probe</span><span class="params">(<span class="keyword">struct</span> i2c_client *client, <span class="type">const</span> <span class="keyword">struct</span> i2c_device_id *id)</span></span><br><span class="line">{</span><br><span class="line"> <span class="comment">/* 函数具体程序 */</span></span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="comment">/* i2c 驱动的 remove 函数 */</span></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">xxx_remove</span><span class="params">(<span class="keyword">struct</span> i2c_client *client)</span></span><br><span class="line">{</span><br><span class="line"><span class="comment">/* 函数具体程序 */</span></span><br><span class="line"> <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="comment">/* 传统匹配方式 ID 列表 */</span></span><br><span class="line"><span class="type">static</span> <span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_device_id</span> <span class="title">xxx_id</span>[] =</span> {</span><br><span class="line"> {<span class="string">"xxx"</span>, <span class="number">0</span>},</span><br><span class="line"> {}</span><br><span class="line">};</span><br><span class="line"></span><br><span class="line"><span class="comment">/* 设备树匹配列表 */</span></span><br><span class="line"><span class="type">static</span> <span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">of_device_id</span> <span class="title">xxx_of_match</span>[] =</span> {</span><br><span class="line"> { .compatible = <span class="string">"xxx"</span> },</span><br><span class="line"> { <span class="comment">/* Sentinel */</span> }</span><br><span class="line">};</span><br><span class="line"></span><br><span class="line"><span class="comment">/* i2c 驱动结构体 */</span></span><br><span class="line"><span class="type">static</span> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_driver</span> <span class="title">xxx_driver</span> =</span> {</span><br><span class="line"> .probe = xxx_probe,</span><br><span class="line"> .remove = xxx_remove,</span><br><span class="line"> .driver = {</span><br><span class="line"> .owner = THIS_MODULE,</span><br><span class="line"> .name = <span class="string">"xxx"</span>,</span><br><span class="line"> .of_match_table = xxx_of_match,</span><br><span class="line"> },</span><br><span class="line"> .id_table = xxx_id,</span><br><span class="line">};</span><br><span class="line"></span><br><span class="line"><span class="comment">/* 驱动入口函数 */</span></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> __init <span class="title function_">xxx_init</span><span class="params">(<span class="type">void</span>)</span></span><br><span class="line">{</span><br><span class="line"> <span class="type">int</span> ret = <span class="number">0</span>;</span><br><span class="line"></span><br><span class="line"> ret = i2c_add_driver(&amp;xxx_driver);</span><br><span class="line"> <span class="keyword">return</span> ret;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="comment">/* 驱动出口函数 */</span></span><br><span class="line"><span class="type">static</span> <span class="type">void</span> __exit <span class="title function_">xxx_exit</span><span class="params">(<span class="type">void</span>)</span></span><br><span class="line">{</span><br><span class="line"> i2c_del_driver(&amp;xxx_driver);</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line">module_init(xxx_init);</span><br><span class="line">module_exit(xxx_exit);</span><br></pre></td></tr></table></figure>

<p>同时Linux也提供了一个宏来简化驱动注册：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">module_i2c_driver(xxx_driver);</span><br></pre></td></tr></table></figure>

<p>宏展开后是：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">static</span> <span class="type">int</span> __init <span class="title function_">xxx_driver_init</span><span class="params">(<span class="type">void</span>)</span></span><br><span class="line">{</span><br><span class="line"><span class="keyword">return</span> i2c_add_driver(&amp;xxx_driver);</span><br><span class="line">}</span><br><span class="line">module_init(xxx_driver_init);</span><br><span class="line"><span class="type">static</span> <span class="type">void</span> __exit <span class="title function_">xxx_driver_exit</span><span class="params">(<span class="type">void</span>)</span></span><br><span class="line">{</span><br><span class="line">i2c_del_driver(&amp;xxx_driver);</span><br><span class="line">}</span><br><span class="line">module_exit(xxx_driver_exit);</span><br></pre></td></tr></table></figure>

<p>可见方便了使用。</p>
<h2 id="设备匹配方式"><a href="#设备匹配方式" class="headerlink" title="设备匹配方式"></a>设备匹配方式</h2><ul>
<li>无设备树时匹配方式</li>
</ul>
<p>老式匹配方式，这里不再多说。需要使用一个<code>i2c_board_info  </code>结构体来描述一个设备。</p>
<ul>
<li>设备树添加方式</li>
</ul>
<p>示例：</p>
<figure class="highlight plaintext"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line">&amp;i2c0 {</span><br><span class="line"> clock-frequency = &lt;100000&gt;;</span><br><span class="line"></span><br><span class="line"> rtc@51 {</span><br><span class="line">  compatible = "nxp,pcf8563";</span><br><span class="line">  reg = &lt;0x51&gt;;</span><br><span class="line"> };</span><br><span class="line">};</span><br></pre></td></tr></table></figure>

<p>对以上，驱动中的of_match表如下：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">/* 匹配列表 */</span></span><br><span class="line"><span class="type">static</span> <span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">of_device_id</span> <span class="title">pcf8563_of_match</span>[] =</span> {</span><br><span class="line">{ .compatible = <span class="string">"zynq-pcf8563"</span> },</span><br><span class="line"> { <span class="comment">/* Sentinel */</span> }</span><br><span class="line">};</span><br></pre></td></tr></table></figure>

<h2 id="实际数据传输函数"><a href="#实际数据传输函数" class="headerlink" title="实际数据传输函数"></a>实际数据传输函数</h2><p>匹配到设备后需要利用IIC传输实际的数据，这里就涉及到一个函数：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">int</span> <span class="title function_">i2c_transfer</span><span class="params">(<span class="keyword">struct</span> i2c_adapter *adap,</span></span><br><span class="line"><span class="params"><span class="keyword">struct</span> i2c_msg *msgs,</span></span><br><span class="line"><span class="params"><span class="type">int</span> num)</span></span><br></pre></td></tr></table></figure>

<p>该函数最终会调用I2C 适配器中 i2c_algorithm 里面的 master_xfer 函数 ，即IIC总线驱动中硬件相关传输函数。</p>
<p>该函数参数如下：</p>
<p><code>adap</code>： 所使用的 I2C 适配器， i2c_client.i2c_adapter。<br><code>msgs</code>： I2C 要发送的一个或多个消息。<br><code>num</code>： 消息数量，也就是 msgs 的数量。<br>返回值： 负值，失败，其他非负值，发送的 msgs 数量。  </p>
<p>i2c_msg定义在<code>include/uapi/linux/i2c.h  </code>:</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br></pre></td><td class="code"><pre><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">i2c_msg</span> {</span></span><br><span class="line"> __u16 addr; <span class="comment">/* 从机地址 */</span></span><br><span class="line"> __u16 flags; <span class="comment">/* 标志 */</span></span><br><span class="line"> <span class="meta">#<span class="keyword">define</span> I2C_M_RD 0x0001 <span class="comment">/* read data, from slave to master */</span></span></span><br><span class="line"><span class="comment">/* I2C_M_RD is guaranteed to be 0x0001! */</span></span><br><span class="line"> <span class="meta">#<span class="keyword">define</span> I2C_M_TEN 0x0010 <span class="comment">/* this is a ten bit chip address */</span></span></span><br><span class="line"> <span class="meta">#<span class="keyword">define</span> I2C_M_RECV_LEN 0x0400 <span class="comment">/* length will be first received byte */</span></span></span><br><span class="line"> <span class="meta">#<span class="keyword">define</span> I2C_M_NO_RD_ACK 0x0800 <span class="comment">/* if I2C_FUNC_PROTOCOL_MANGLING */</span></span></span><br><span class="line"> <span class="meta">#<span class="keyword">define</span> I2C_M_IGNORE_NAK 0x1000 <span class="comment">/* if I2C_FUNC_PROTOCOL_MANGLING */</span></span></span><br><span class="line"> <span class="meta">#<span class="keyword">define</span> I2C_M_REV_DIR_ADDR 0x2000 <span class="comment">/* if I2C_FUNC_PROTOCOL_MANGLING */</span></span></span><br><span class="line"> <span class="meta">#<span class="keyword">define</span> I2C_M_NOSTART 0x4000 <span class="comment">/* if I2C_FUNC_NOSTART */</span></span></span><br><span class="line"> <span class="meta">#<span class="keyword">define</span> I2C_M_STOP 0x8000 <span class="comment">/* if I2C_FUNC_PROTOCOL_MANGLING */</span></span></span><br><span class="line"> __u16 len; <span class="comment">/* 消息（数据）长度 */</span></span><br><span class="line"> __u8 *buf; <span class="comment">/* 消息（数据）地址 */</span></span><br><span class="line">};</span><br></pre></td></tr></table></figure>

<p>传输前一般都会先构建好msg。</p>
<p>使用该函数读取I2C设备寄存器的例子：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br></pre></td><td class="code"><pre><span class="line"> <span class="comment">/* 设备结构体 */</span></span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">xxx_dev</span> {</span></span><br><span class="line"> ......</span><br><span class="line"> <span class="type">void</span> *private_data; <span class="comment">/* 私有数据，一般会设置为 i2c_client */</span></span><br><span class="line">};</span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * @description : 读取 I2C 设备多个寄存器数据</span></span><br><span class="line"><span class="comment"> * @param – dev : I2C 设备</span></span><br><span class="line"><span class="comment"> * @param – reg : 要读取的寄存器首地址</span></span><br><span class="line"><span class="comment"> * @param – val : 读取到的数据</span></span><br><span class="line"><span class="comment"> * @param – len : 要读取的数据长度</span></span><br><span class="line"><span class="comment"> * @return : 操作结果</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">xxx_read_regs</span><span class="params">(<span class="keyword">struct</span> xxx_dev *dev, u8 reg, <span class="type">void</span> *val, <span class="type">int</span> len)</span></span><br><span class="line">{</span><br><span class="line"> <span class="type">int</span> ret;</span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_msg</span> <span class="title">msg</span>[2];</span></span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_client</span> *<span class="title">client</span> =</span> (<span class="keyword">struct</span> i2c_client *)dev-&gt;private_data;</span><br><span class="line"></span><br><span class="line"> <span class="comment">/* msg[0]，第一条写消息，发送要读取的寄存器首地址 */</span></span><br><span class="line"> msg[<span class="number">0</span>].addr = client-&gt;addr; <span class="comment">/* I2C 器件地址 */</span></span><br><span class="line"> msg[<span class="number">0</span>].flags = <span class="number">0</span>; <span class="comment">/* 标记为发送数据 */</span></span><br><span class="line"> msg[<span class="number">0</span>].buf = &amp;reg; <span class="comment">/* 读取的首地址 */</span></span><br><span class="line"> msg[<span class="number">0</span>].len = <span class="number">1</span>; <span class="comment">/* reg 长度 */</span></span><br><span class="line"></span><br><span class="line"> <span class="comment">/* msg[1]，第二条读消息，读取寄存器数据 */</span></span><br><span class="line"> msg[<span class="number">1</span>].addr = client-&gt;addr; <span class="comment">/* I2C 器件地址 */</span></span><br><span class="line"> msg[<span class="number">1</span>].flags = I2C_M_RD; <span class="comment">/* 标记为读取数据 */</span></span><br><span class="line"> msg[<span class="number">1</span>].buf = val; <span class="comment">/* 读取数据缓冲区 */</span></span><br><span class="line"> msg[<span class="number">1</span>].len = len; <span class="comment">/* 要读取的数据长度 */</span></span><br><span class="line"></span><br><span class="line"> ret = i2c_transfer(client-&gt;adapter, msg, <span class="number">2</span>);</span><br><span class="line"> <span class="keyword">if</span>(ret == <span class="number">2</span>) {</span><br><span class="line"> ret = <span class="number">0</span>;</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> ret = -EREMOTEIO;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> ret;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"> <span class="comment">/*</span></span><br><span class="line"><span class="comment"> * @description : 向 I2C 设备多个寄存器写入数据</span></span><br><span class="line"><span class="comment"> * @param – dev : 要写入的设备结构体</span></span><br><span class="line"><span class="comment"> * @param – reg : 要写入的寄存器首地址</span></span><br><span class="line"><span class="comment"> * @param – val : 要写入的数据缓冲区</span></span><br><span class="line"><span class="comment"> * @param – len : 要写入的数据长度</span></span><br><span class="line"><span class="comment"> * @return : 操作结果</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="type">static</span> s32 <span class="title function_">xxx_write_regs</span><span class="params">(<span class="keyword">struct</span> xxx_dev *dev, u8 reg, u8 *buf, u8 len)</span></span><br><span class="line">{</span><br><span class="line"> u8 b[<span class="number">256</span>];</span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_msg</span> <span class="title">msg</span>;</span></span><br><span class="line"> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_client</span> *<span class="title">client</span> =</span> (<span class="keyword">struct</span> i2c_client *)dev-&gt;private_data;</span><br><span class="line"></span><br><span class="line"> b[<span class="number">0</span>] = reg; <span class="comment">/* 寄存器首地址 */</span></span><br><span class="line"> <span class="built_in">memcpy</span>(&amp;b[<span class="number">1</span>],buf,len); <span class="comment">/* 将要发送的数据拷贝到数组 b 里面 */</span></span><br><span class="line"></span><br><span class="line"> msg.addr = client-&gt;addr; <span class="comment">/* I2C 器件地址 */</span></span><br><span class="line"> msg.flags = <span class="number">0</span>; <span class="comment">/* 标记为写数据 */</span></span><br><span class="line">    </span><br><span class="line"> msg.buf = b; <span class="comment">/* 要发送的数据缓冲区 */</span></span><br><span class="line"> msg.len = len + <span class="number">1</span>; <span class="comment">/* 要发送的数据长度 */</span></span><br><span class="line"></span><br><span class="line"> <span class="keyword">return</span> i2c_transfer(client-&gt;adapter, &amp;msg, <span class="number">1</span>);</span><br><span class="line">}</span><br></pre></td></tr></table></figure>

<p>除此之外还有两个API函数用来收发数据，最后都会调用i2c_transfer。</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">int</span> <span class="title function_">i2c_master_send</span><span class="params">(<span class="type">const</span> <span class="keyword">struct</span> i2c_client *client,</span></span><br><span class="line"><span class="params">	<span class="type">const</span> <span class="type">char</span> *buf,</span></span><br><span class="line"><span class="params">	<span class="type">int</span> count)</span></span><br></pre></td></tr></table></figure>

<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="type">int</span> <span class="title function_">i2c_master_recv</span><span class="params">(<span class="type">const</span> <span class="keyword">struct</span> i2c_client *client,</span></span><br><span class="line"><span class="params">	<span class="type">char</span> *buf,</span></span><br><span class="line"><span class="params">	<span class="type">int</span> count)</span></span><br></pre></td></tr></table></figure>

<p>count： 要接收的数据字节数，要小于 64KB，因为 i2c_msg 的 len 成员变量是一个 u16(无<br>符号 16 位)类型的数据。  </p>
<h2 id="实战-MPU6050驱动的编写"><a href="#实战-MPU6050驱动的编写" class="headerlink" title="实战-MPU6050驱动的编写"></a>实战-MPU6050驱动的编写</h2><p>首先，在设备树中添加MPU6050节点：</p>
<figure class="highlight plaintext"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br></pre></td><td class="code"><pre><span class="line">&amp;i2c0{</span><br><span class="line">	clock-frequency=&lt;100000&gt;;</span><br><span class="line">	</span><br><span class="line">	mpu6050@68{</span><br><span class="line">		compatible = "atk,mpu6050";</span><br><span class="line">		reg=&lt;0x68&gt;;</span><br><span class="line">	};</span><br><span class="line">};</span><br></pre></td></tr></table></figure>

<p>驱动中编写如下代码：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br><span class="line">95</span><br><span class="line">96</span><br><span class="line">97</span><br><span class="line">98</span><br><span class="line">99</span><br><span class="line">100</span><br><span class="line">101</span><br><span class="line">102</span><br><span class="line">103</span><br><span class="line">104</span><br><span class="line">105</span><br><span class="line">106</span><br><span class="line">107</span><br><span class="line">108</span><br><span class="line">109</span><br><span class="line">110</span><br><span class="line">111</span><br><span class="line">112</span><br><span class="line">113</span><br><span class="line">114</span><br><span class="line">115</span><br><span class="line">116</span><br><span class="line">117</span><br><span class="line">118</span><br><span class="line">119</span><br><span class="line">120</span><br><span class="line">121</span><br><span class="line">122</span><br><span class="line">123</span><br><span class="line">124</span><br><span class="line">125</span><br><span class="line">126</span><br><span class="line">127</span><br><span class="line">128</span><br><span class="line">129</span><br><span class="line">130</span><br><span class="line">131</span><br><span class="line">132</span><br><span class="line">133</span><br><span class="line">134</span><br><span class="line">135</span><br><span class="line">136</span><br><span class="line">137</span><br><span class="line">138</span><br><span class="line">139</span><br><span class="line">140</span><br><span class="line">141</span><br><span class="line">142</span><br><span class="line">143</span><br><span class="line">144</span><br><span class="line">145</span><br><span class="line">146</span><br><span class="line">147</span><br><span class="line">148</span><br><span class="line">149</span><br><span class="line">150</span><br><span class="line">151</span><br><span class="line">152</span><br><span class="line">153</span><br><span class="line">154</span><br><span class="line">155</span><br><span class="line">156</span><br><span class="line">157</span><br><span class="line">158</span><br><span class="line">159</span><br><span class="line">160</span><br><span class="line">161</span><br><span class="line">162</span><br><span class="line">163</span><br><span class="line">164</span><br><span class="line">165</span><br><span class="line">166</span><br><span class="line">167</span><br><span class="line">168</span><br><span class="line">169</span><br><span class="line">170</span><br><span class="line">171</span><br><span class="line">172</span><br><span class="line">173</span><br><span class="line">174</span><br><span class="line">175</span><br><span class="line">176</span><br><span class="line">177</span><br><span class="line">178</span><br><span class="line">179</span><br><span class="line">180</span><br><span class="line">181</span><br><span class="line">182</span><br><span class="line">183</span><br><span class="line">184</span><br><span class="line">185</span><br><span class="line">186</span><br><span class="line">187</span><br><span class="line">188</span><br><span class="line">189</span><br><span class="line">190</span><br><span class="line">191</span><br><span class="line">192</span><br><span class="line">193</span><br><span class="line">194</span><br><span class="line">195</span><br><span class="line">196</span><br><span class="line">197</span><br><span class="line">198</span><br><span class="line">199</span><br><span class="line">200</span><br><span class="line">201</span><br><span class="line">202</span><br><span class="line">203</span><br><span class="line">204</span><br><span class="line">205</span><br><span class="line">206</span><br><span class="line">207</span><br><span class="line">208</span><br><span class="line">209</span><br><span class="line">210</span><br><span class="line">211</span><br><span class="line">212</span><br><span class="line">213</span><br><span class="line">214</span><br><span class="line">215</span><br><span class="line">216</span><br><span class="line">217</span><br><span class="line">218</span><br><span class="line">219</span><br><span class="line">220</span><br><span class="line">221</span><br><span class="line">222</span><br><span class="line">223</span><br><span class="line">224</span><br><span class="line">225</span><br><span class="line">226</span><br><span class="line">227</span><br><span class="line">228</span><br><span class="line">229</span><br><span class="line">230</span><br><span class="line">231</span><br><span class="line">232</span><br><span class="line">233</span><br><span class="line">234</span><br><span class="line">235</span><br><span class="line">236</span><br><span class="line">237</span><br><span class="line">238</span><br><span class="line">239</span><br><span class="line">240</span><br><span class="line">241</span><br><span class="line">242</span><br><span class="line">243</span><br><span class="line">244</span><br><span class="line">245</span><br><span class="line">246</span><br><span class="line">247</span><br><span class="line">248</span><br><span class="line">249</span><br><span class="line">250</span><br><span class="line">251</span><br><span class="line">252</span><br><span class="line">253</span><br><span class="line">254</span><br><span class="line">255</span><br><span class="line">256</span><br><span class="line">257</span><br><span class="line">258</span><br><span class="line">259</span><br><span class="line">260</span><br><span class="line">261</span><br><span class="line">262</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">"mpu6050.h"</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;linux/module.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;linux/cdev.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;linux/device.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;linux/i2c.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;linux/uaccess.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;linux/delay.h&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;linux/fs.h&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> MPU6050_CNT	1</span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> MPU6050_NAME	<span class="string">"mpu6050"</span></span></span><br><span class="line"></span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">mpu6050_dev</span> {</span></span><br><span class="line">    <span class="type">dev_t</span> devid;				<span class="comment">/* 设备号 	 */</span></span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="title">cdev</span> <span class="title">cdev</span>;</span>			<span class="comment">/* cdev 	*/</span></span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="keyword">class</span> *<span class="keyword">class</span>;</span>		<span class="comment">/* 类 		*/</span></span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="title">device</span> *<span class="title">device</span>;</span>		<span class="comment">/* 设备 	 */</span></span><br><span class="line"></span><br><span class="line">    <span class="type">int</span> major;					<span class="comment">/* 主设备号 */</span></span><br><span class="line">    <span class="type">void</span> *private_data;			<span class="comment">/* 私有数据用于存储client*/</span></span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> gyro_x_adc;		<span class="comment">/* 陀螺仪X轴原始值 	 */</span></span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> gyro_y_adc;		<span class="comment">/* 陀螺仪Y轴原始值		*/</span></span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> gyro_z_adc;		<span class="comment">/* 陀螺仪Z轴原始值 		*/</span></span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> accel_x_adc;		<span class="comment">/* 加速度计X轴原始值 	*/</span></span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> accel_y_adc;		<span class="comment">/* 加速度计Y轴原始值	*/</span></span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> accel_z_adc;		<span class="comment">/* 加速度计Z轴原始值 	*/</span></span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> temp_adc;		<span class="comment">/* 温度原始值 			*/</span></span><br><span class="line">};</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="class"><span class="keyword">struct</span> <span class="title">mpu6050_dev</span> <span class="title">mpu6050dev</span>;</span></span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">mpu6050_release</span><span class="params">(<span class="keyword">struct</span> inode *inode, <span class="keyword">struct</span> file *filp)</span></span><br><span class="line">{</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">mpu6050_open</span><span class="params">(<span class="keyword">struct</span> inode *inode, <span class="keyword">struct</span> file *filp)</span></span><br><span class="line">{</span><br><span class="line">    filp-&gt;private_data = &amp;mpu6050dev; <span class="comment">/* 设置私有数据 */</span></span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> s32 <span class="title function_">mpu6050_write_regs</span><span class="params">(<span class="keyword">struct</span> mpu6050_dev *dev, u8 reg, u8 *buf, u8 len)</span></span><br><span class="line">{</span><br><span class="line">    u8 b[<span class="number">256</span>];</span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="title">i2c_msg</span> <span class="title">msg</span>;</span></span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="title">i2c_client</span> *<span class="title">client</span> =</span> (<span class="keyword">struct</span> i2c_client *)dev-&gt;private_data;</span><br><span class="line"></span><br><span class="line">    b[<span class="number">0</span>] = reg;					<span class="comment">/* 寄存器首地址 */</span></span><br><span class="line">    <span class="built_in">memcpy</span>(&amp;b[<span class="number">1</span>],buf,len);		<span class="comment">/* 将要写入的数据拷贝到数组b里面 */</span></span><br><span class="line"></span><br><span class="line">    msg.addr = client-&gt;addr;	<span class="comment">/* mpu6050地址 */</span></span><br><span class="line">    msg.flags = <span class="number">0</span>;				<span class="comment">/* 标记为写数据 */</span></span><br><span class="line"></span><br><span class="line">    msg.buf = b;				<span class="comment">/* 要写入的数据缓冲区 */</span></span><br><span class="line">    msg.len = len + <span class="number">1</span>;			<span class="comment">/* 要写入的数据长度 */</span></span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> i2c_transfer(client-&gt;adapter, &amp;msg, <span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">void</span> <span class="title function_">mpu6050_write_onereg</span><span class="params">(<span class="keyword">struct</span> mpu6050_dev *dev, u8 reg, u8 data)</span></span><br><span class="line">{</span><br><span class="line">    u8 buf = <span class="number">0</span>;</span><br><span class="line">    buf = data;</span><br><span class="line">    mpu6050_write_regs(dev, reg, &amp;buf, <span class="number">1</span>);</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">mpu6050_read_regs</span><span class="params">(<span class="keyword">struct</span> mpu6050_dev *dev, u8 reg, <span class="type">void</span> *val, <span class="type">int</span> len)</span></span><br><span class="line">{</span><br><span class="line">    <span class="type">int</span> ret;</span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="title">i2c_msg</span> <span class="title">msg</span>[2];</span></span><br><span class="line">    <span class="class"><span class="keyword">struct</span> <span class="title">i2c_client</span> *<span class="title">client</span> =</span> (<span class="keyword">struct</span> i2c_client *)dev-&gt;private_data;</span><br><span class="line"></span><br><span class="line">    <span class="comment">/* msg[0]为发送要读取的首地址 */</span></span><br><span class="line">    msg[<span class="number">0</span>].addr = client-&gt;addr;			<span class="comment">/*   */</span></span><br><span class="line">    msg[<span class="number">0</span>].flags = <span class="number">0</span>;					<span class="comment">/* 标记为发送数据 */</span></span><br><span class="line">    msg[<span class="number">0</span>].buf = &amp;reg;					<span class="comment">/* 读取的首地址 */</span></span><br><span class="line">    msg[<span class="number">0</span>].len = <span class="number">1</span>;						<span class="comment">/* reg长度*/</span></span><br><span class="line"></span><br><span class="line">    <span class="comment">/* msg[1]读取数据 */</span></span><br><span class="line">    msg[<span class="number">1</span>].addr = client-&gt;addr;			<span class="comment">/*   */</span></span><br><span class="line">    msg[<span class="number">1</span>].flags = I2C_M_RD;			<span class="comment">/* 标记为读取数据*/</span></span><br><span class="line">    msg[<span class="number">1</span>].buf = val;					<span class="comment">/* 读取数据缓冲区 */</span></span><br><span class="line">    msg[<span class="number">1</span>].len = len;					<span class="comment">/* 要读取的数据长度*/</span></span><br><span class="line"></span><br><span class="line">    ret = i2c_transfer(client-&gt;adapter, msg, <span class="number">2</span>);</span><br><span class="line">    <span class="keyword">if</span>(ret == <span class="number">2</span>) {</span><br><span class="line">        ret = <span class="number">0</span>;</span><br><span class="line">    } <span class="keyword">else</span> {</span><br><span class="line">        printk(<span class="string">"i2c rd failed=%d reg=%06x len=%d\n"</span>,ret, reg, len);</span><br><span class="line">        ret = -EREMOTEIO;</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">return</span> ret;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">unsigned</span> <span class="type">char</span> <span class="title function_">mpu6050_read_onereg</span><span class="params">(<span class="keyword">struct</span> mpu6050_dev *dev, u8 reg)</span></span><br><span class="line">{</span><br><span class="line">    u8 data = <span class="number">0</span>;</span><br><span class="line"></span><br><span class="line">    mpu6050_read_regs(dev, reg, &amp;data, <span class="number">1</span>);</span><br><span class="line">    <span class="keyword">return</span> data;</span><br><span class="line"></span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="type">void</span> <span class="title function_">mpu6050_readdata</span><span class="params">(<span class="keyword">struct</span> mpu6050_dev *dev)</span></span><br><span class="line">{</span><br><span class="line">    <span class="type">unsigned</span> <span class="type">char</span> data[<span class="number">14</span>];</span><br><span class="line">    mpu6050_read_regs(dev, MPU6050_RA_ACCEL_XOUT_H, data, <span class="number">14</span>);</span><br><span class="line"></span><br><span class="line">    dev-&gt;accel_x_adc = (<span class="type">signed</span> <span class="type">short</span>)((data[<span class="number">0</span>] &lt;&lt; <span class="number">8</span>) | data[<span class="number">1</span>]);</span><br><span class="line">    dev-&gt;accel_y_adc = (<span class="type">signed</span> <span class="type">short</span>)((data[<span class="number">2</span>] &lt;&lt; <span class="number">8</span>) | data[<span class="number">3</span>]);</span><br><span class="line">    dev-&gt;accel_z_adc = (<span class="type">signed</span> <span class="type">short</span>)((data[<span class="number">4</span>] &lt;&lt; <span class="number">8</span>) | data[<span class="number">5</span>]);</span><br><span class="line">    dev-&gt;temp_adc    = (<span class="type">signed</span> <span class="type">short</span>)((data[<span class="number">6</span>] &lt;&lt; <span class="number">8</span>) | data[<span class="number">7</span>]);</span><br><span class="line">    dev-&gt;gyro_x_adc  = (<span class="type">signed</span> <span class="type">short</span>)((data[<span class="number">8</span>] &lt;&lt; <span class="number">8</span>) | data[<span class="number">9</span>]);</span><br><span class="line">    dev-&gt;gyro_y_adc  = (<span class="type">signed</span> <span class="type">short</span>)((data[<span class="number">10</span>] &lt;&lt; <span class="number">8</span>) | data[<span class="number">11</span>]);</span><br><span class="line">    dev-&gt;gyro_z_adc  = (<span class="type">signed</span> <span class="type">short</span>)((data[<span class="number">12</span>] &lt;&lt; <span class="number">8</span>) | data[<span class="number">13</span>]);</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">ssize_t</span> <span class="title function_">mpu6050_read</span><span class="params">(<span class="keyword">struct</span> file *filp, <span class="type">char</span> __user *buf, <span class="type">size_t</span> cnt, <span class="type">loff_t</span> *off)</span></span><br><span class="line">{</span><br><span class="line"><span class="type">signed</span> <span class="type">int</span> data[<span class="number">7</span>];</span><br><span class="line"><span class="type">long</span> err = <span class="number">0</span>;</span><br><span class="line"><span class="class"><span class="keyword">struct</span> <span class="title">mpu6050_dev</span> *<span class="title">dev</span> =</span> (<span class="keyword">struct</span> mpu6050_dev *)filp-&gt;private_data;</span><br><span class="line"></span><br><span class="line">mpu6050_readdata(dev);</span><br><span class="line">data[<span class="number">0</span>] = dev-&gt;gyro_x_adc;</span><br><span class="line">data[<span class="number">1</span>] = dev-&gt;gyro_y_adc;</span><br><span class="line">data[<span class="number">2</span>] = dev-&gt;gyro_z_adc;</span><br><span class="line">data[<span class="number">3</span>] = dev-&gt;accel_x_adc;</span><br><span class="line">data[<span class="number">4</span>] = dev-&gt;accel_y_adc;</span><br><span class="line">data[<span class="number">5</span>] = dev-&gt;accel_z_adc;</span><br><span class="line">data[<span class="number">6</span>] = dev-&gt;temp_adc;</span><br><span class="line"></span><br><span class="line"><span class="comment">//printk("mpu6050 Read Data:x_adc:%d\r\n",data[0]);</span></span><br><span class="line">err = copy_to_user(buf, data, <span class="keyword">sizeof</span>(data));</span><br><span class="line"><span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="comment">/* mpu6050操作函数 */</span></span><br><span class="line"><span class="type">static</span> <span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">file_operations</span> <span class="title">mpu6050_ops</span> =</span> {</span><br><span class="line">        .owner = THIS_MODULE,</span><br><span class="line">        .open = mpu6050_open,</span><br><span class="line">        .read = mpu6050_read,</span><br><span class="line">        .release = mpu6050_release,</span><br><span class="line">};</span><br><span class="line"></span><br><span class="line"><span class="comment">/**</span></span><br><span class="line"><span class="comment"> * mpu6050初始化函数</span></span><br><span class="line"><span class="comment"> */</span></span><br><span class="line"><span class="type">void</span> <span class="title function_">mpu6050_reginit</span><span class="params">(<span class="type">void</span>)</span></span><br><span class="line">{</span><br><span class="line">    u8 value = <span class="number">0</span>;</span><br><span class="line"></span><br><span class="line">    mpu6050_write_onereg(&amp;mpu6050dev, MPU6050_RA_PWR_MGMT_1, <span class="number">0x80</span>);<span class="comment">//复位设备</span></span><br><span class="line">    mdelay(<span class="number">50</span>);</span><br><span class="line">    mpu6050_write_onereg(&amp;mpu6050dev, MPU6050_RA_PWR_MGMT_1, <span class="number">0x01</span>);<span class="comment">//退出休眠模式,选择X轴PLL作为时钟</span></span><br><span class="line">    mdelay(<span class="number">50</span>);</span><br><span class="line"></span><br><span class="line">    value = mpu6050_read_onereg(&amp;mpu6050dev, MPU6050_RA_WHO_AM_I);</span><br><span class="line">    printk(<span class="string">"mpu6050 ID = %#X\r\n"</span>, value);</span><br><span class="line"></span><br><span class="line">    mpu6050_write_onereg(&amp;mpu6050dev, MPU6050_RA_SMPLRT_DIV, <span class="number">0x00</span>); 	<span class="comment">/* 输出速率是内部采样率					*/</span></span><br><span class="line">    <span class="comment">//设置量程为最小，提高精度</span></span><br><span class="line">    mpu6050_write_onereg(&amp;mpu6050dev, MPU6050_RA_GYRO_CONFIG, <span class="number">0x00</span>); 	<span class="comment">/* 陀螺仪±250dps量程 */</span></span><br><span class="line">    mpu6050_write_onereg(&amp;mpu6050dev, MPU6050_RA_ACCEL_CONFIG, <span class="number">0x00</span>); 	<span class="comment">/* 加速度计±2G量程 */</span></span><br><span class="line"><span class="comment">//    mpu6050_write_onereg(&amp;mpu6050dev, MPU6050_RA_GYRO_CONFIG, 0x18); 	/* 陀螺仪±2000dps量程 				*/</span></span><br><span class="line"><span class="comment">//    mpu6050_write_onereg(&amp;mpu6050dev, MPU6050_RA_ACCEL_CONFIG, 0x18); 	/* 加速度计±16G量程 					*/</span></span><br><span class="line">    mpu6050_write_onereg(&amp;mpu6050dev, MPU6050_RA_CONFIG, <span class="number">0x04</span>); 		<span class="comment">/* 陀螺仪低通滤波BW=20Hz 				*/</span></span><br><span class="line">    mpu6050_write_onereg(&amp;mpu6050dev, MPU6050_RA_PWR_MGMT_2, <span class="number">0x00</span>); 	<span class="comment">/* 打开加速度计和陀螺仪所有轴 				*/</span></span><br><span class="line">    mpu6050_write_onereg(&amp;mpu6050dev, MPU6050_RA_FIFO_EN, <span class="number">0x00</span>);		<span class="comment">/* 关闭FIFO						*/</span></span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">mpu6050_probe</span><span class="params">(<span class="keyword">struct</span> i2c_client *client, <span class="type">const</span> <span class="keyword">struct</span> i2c_device_id *id)</span></span><br><span class="line">{</span><br><span class="line">    <span class="type">int</span> ret = <span class="number">0</span>;</span><br><span class="line"></span><br><span class="line">    <span class="comment">/* 1、构建设备号 */</span></span><br><span class="line">    <span class="keyword">if</span> (mpu6050dev.major) {</span><br><span class="line">        mpu6050dev.devid = MKDEV(mpu6050dev.major, <span class="number">0</span>);</span><br><span class="line">        ret=register_chrdev_region(mpu6050dev.devid, MPU6050_CNT, MPU6050_NAME);</span><br><span class="line">    } <span class="keyword">else</span> {</span><br><span class="line">        ret=alloc_chrdev_region(&amp;mpu6050dev.devid, <span class="number">0</span>, MPU6050_CNT, MPU6050_NAME);</span><br><span class="line">        mpu6050dev.major = MAJOR(mpu6050dev.devid);</span><br><span class="line">    }</span><br><span class="line">    <span class="keyword">if</span>(ret) <span class="keyword">return</span> ret;</span><br><span class="line"></span><br><span class="line">    <span class="comment">/* 2、注册cdev设备 */</span></span><br><span class="line">    cdev_init(&amp;mpu6050dev.cdev, &amp;mpu6050_ops);</span><br><span class="line">    ret=cdev_add(&amp;mpu6050dev.cdev, mpu6050dev.devid, MPU6050_CNT);</span><br><span class="line">    <span class="keyword">if</span>(ret) <span class="keyword">goto</span> out1;</span><br><span class="line"></span><br><span class="line">    <span class="comment">/* 3、创建类 */</span></span><br><span class="line">    mpu6050dev.class = class_create(THIS_MODULE, MPU6050_NAME);</span><br><span class="line">    <span class="keyword">if</span> (IS_ERR(mpu6050dev.class)) {</span><br><span class="line">        ret=PTR_ERR(mpu6050dev.class);</span><br><span class="line">        <span class="keyword">goto</span> out2;</span><br><span class="line">    }</span><br><span class="line"></span><br><span class="line">    <span class="comment">/* 4、创建设备 */</span></span><br><span class="line">    mpu6050dev.device = device_create(mpu6050dev.class, &amp;client-&gt;dev, mpu6050dev.devid, <span class="literal">NULL</span>, MPU6050_NAME);</span><br><span class="line">    <span class="keyword">if</span> (IS_ERR(mpu6050dev.device)) {</span><br><span class="line">        ret = PTR_ERR(mpu6050dev.device);</span><br><span class="line">        <span class="keyword">goto</span> out3;</span><br><span class="line">    }</span><br><span class="line"></span><br><span class="line">    mpu6050dev.private_data = client; <span class="comment">/* 设置私有数据 */</span></span><br><span class="line"></span><br><span class="line">    mpu6050_reginit();</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line"><span class="comment">//分级进行反注册设备</span></span><br><span class="line">out3:</span><br><span class="line">    class_destroy(mpu6050dev.class);</span><br><span class="line">out2:</span><br><span class="line">    cdev_del(&amp;mpu6050dev.cdev);</span><br><span class="line">out1:</span><br><span class="line">    unregister_chrdev_region(mpu6050dev.devid,MPU6050_CNT);</span><br><span class="line"></span><br><span class="line">    <span class="keyword">return</span> ret;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="type">int</span> <span class="title function_">mpu6050_remove</span><span class="params">(<span class="keyword">struct</span> i2c_client *client)</span></span><br><span class="line">{</span><br><span class="line">    <span class="comment">/* 删除设备 */</span></span><br><span class="line">    cdev_del(&amp;mpu6050dev.cdev);</span><br><span class="line">    unregister_chrdev_region(mpu6050dev.devid, MPU6050_CNT);</span><br><span class="line"></span><br><span class="line">    <span class="comment">/* 注销掉类和设备 */</span></span><br><span class="line">    device_destroy(mpu6050dev.class, mpu6050dev.devid);</span><br><span class="line">    class_destroy(mpu6050dev.class);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="comment">/* 传统匹配方式ID列表 */</span></span><br><span class="line"><span class="type">static</span> <span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_device_id</span> <span class="title">mpu6050_id</span>[] =</span> {</span><br><span class="line">        {<span class="string">"atk,mpu6050"</span>, <span class="number">0</span>},</span><br><span class="line">        {}</span><br><span class="line">};</span><br><span class="line"></span><br><span class="line"><span class="comment">/* 设备树匹配列表 */</span></span><br><span class="line"><span class="type">static</span> <span class="type">const</span> <span class="class"><span class="keyword">struct</span> <span class="title">of_device_id</span> <span class="title">mpu6050_of_match</span>[] =</span> {</span><br><span class="line">        { .compatible = <span class="string">"atk,mpu6050"</span> },</span><br><span class="line">        { <span class="comment">/* Sentinel */</span> }</span><br><span class="line">};</span><br><span class="line"></span><br><span class="line"><span class="type">static</span> <span class="class"><span class="keyword">struct</span> <span class="title">i2c_driver</span> <span class="title">mpu6050_driver</span> =</span> {</span><br><span class="line">        .probe = mpu6050_probe,<span class="comment">//匹配到设备时调用</span></span><br><span class="line">        .remove = mpu6050_remove,</span><br><span class="line">        .driver = {</span><br><span class="line">                .owner = THIS_MODULE,</span><br><span class="line">                .name = <span class="string">"mpu6050"</span>,</span><br><span class="line">                .of_match_table = mpu6050_of_match,<span class="comment">//设备匹配表</span></span><br><span class="line">        },</span><br><span class="line">        .id_table = mpu6050_id,</span><br><span class="line">};</span><br><span class="line"></span><br><span class="line"></span><br><span class="line">module_i2c_driver(mpu6050_driver);</span><br><span class="line"></span><br><span class="line">MODULE_LICENSE(<span class="string">"GPL"</span>);</span><br><span class="line">MODULE_AUTHOR(<span class="string">"LO"</span>);</span><br><span class="line"></span><br></pre></td></tr></table></figure>



<p>编写测试APP：</p>
<figure class="highlight c"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">"stdio.h"</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">"unistd.h"</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">"fcntl.h"</span></span></span><br><span class="line"></span><br><span class="line"></span><br><span class="line"><span class="type">int</span> <span class="title function_">main</span><span class="params">(<span class="type">int</span> argc, <span class="type">char</span> *argv[])</span></span><br><span class="line">{</span><br><span class="line">    <span class="type">int</span> i=<span class="number">10</span>;</span><br><span class="line">    <span class="type">int</span> fd;</span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> buffer[<span class="number">7</span>];</span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> gyro_x_adc, gyro_y_adc, gyro_z_adc;</span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> accel_x_adc, accel_y_adc, accel_z_adc;</span><br><span class="line">    <span class="type">signed</span> <span class="type">int</span> temp_adc;</span><br><span class="line"></span><br><span class="line">    <span class="type">float</span> gyro_x_act, gyro_y_act, gyro_z_act;</span><br><span class="line">    <span class="type">float</span> accel_x_act, accel_y_act, accel_z_act;</span><br><span class="line">    <span class="type">float</span> temp_act;</span><br><span class="line"></span><br><span class="line">    <span class="type">int</span> ret = <span class="number">0</span>;</span><br><span class="line">    <span class="type">char</span>* filename = <span class="string">"/dev/mpu6050"</span>;</span><br><span class="line">    fd = open(filename, O_RDWR);</span><br><span class="line">    <span class="keyword">if</span>(fd &lt; <span class="number">0</span>) {</span><br><span class="line">        <span class="built_in">printf</span>(<span class="string">"can't open file %s\r\n"</span>, filename);</span><br><span class="line">        <span class="keyword">return</span> <span class="number">-1</span>;</span><br><span class="line">    }</span><br><span class="line">    <span class="built_in">printf</span>(<span class="string">"Start Read.\r\n"</span>);</span><br><span class="line">    <span class="keyword">while</span> (i--) {</span><br><span class="line">        ret = read(fd, buffer, <span class="keyword">sizeof</span>(buffer));</span><br><span class="line">        <span class="keyword">if</span>(ret == <span class="number">0</span>) {</span><br><span class="line">            gyro_x_adc = buffer[<span class="number">0</span>];</span><br><span class="line">            gyro_y_adc = buffer[<span class="number">1</span>];</span><br><span class="line">            gyro_z_adc = buffer[<span class="number">2</span>];</span><br><span class="line">            accel_x_adc = buffer[<span class="number">3</span>];</span><br><span class="line">            accel_y_adc = buffer[<span class="number">4</span>];</span><br><span class="line">            accel_z_adc = buffer[<span class="number">5</span>];</span><br><span class="line">            temp_adc = buffer[<span class="number">6</span>];</span><br><span class="line"></span><br><span class="line">            gyro_x_act = (<span class="type">float</span>)(gyro_x_adc)  / <span class="number">16.4</span>;</span><br><span class="line">            gyro_y_act = (<span class="type">float</span>)(gyro_y_adc)  / <span class="number">16.4</span>;</span><br><span class="line">            gyro_z_act = (<span class="type">float</span>)(gyro_z_adc)  / <span class="number">16.4</span>;</span><br><span class="line">            accel_x_act = (<span class="type">float</span>)(accel_x_adc) / <span class="number">2048</span>;</span><br><span class="line">            accel_y_act = (<span class="type">float</span>)(accel_y_adc) / <span class="number">2048</span>;</span><br><span class="line">            accel_z_act = (<span class="type">float</span>)(accel_z_adc) / <span class="number">2048</span>;</span><br><span class="line">            temp_act = ((<span class="type">float</span>)(temp_adc)/ <span class="number">340</span> )  + <span class="number">36.53</span>;</span><br><span class="line"></span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">"\r\nADC value:\r\n"</span>);</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">"gx = %d, gy = %d, gz = %d\r\n"</span>, gyro_x_adc, gyro_y_adc, gyro_z_adc);</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">"ax = %d, ay = %d, az = %d\r\n"</span>, accel_x_adc, accel_y_adc, accel_z_adc);</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">"temp = %d\r\n"</span>, temp_adc);</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">"TRUE value:"</span>);</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">"act gx = %.2f°/S, act gy = %.2f°/S, act gz = %.2f°/S\r\n"</span>, gyro_x_act, gyro_y_act, gyro_z_act);</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">"act ax = %.2fg, act ay = %.2fg, act az = %.2fg\r\n"</span>, accel_x_act, accel_y_act, accel_z_act);</span><br><span class="line">            <span class="built_in">printf</span>(<span class="string">"act temp = %.2f°C\r\n"</span>, temp_act);</span><br><span class="line">        }</span><br><span class="line">        usleep(<span class="number">1000000</span>);</span><br><span class="line">    }</span><br><span class="line">    close(fd);</span><br><span class="line">    <span class="keyword">return</span> <span class="number">0</span>;</span><br><span class="line">}</span><br><span class="line"></span><br></pre></td></tr></table></figure>


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            <h3 class="toc-title">文章目录</h3>
            <ol class="toc"><li class="toc-item toc-level-1"><a class="toc-link" href="#ZYNQ%E5%AD%A6%E4%B9%A0%E7%AC%94%E8%AE%B0-IIC%E9%A9%B1%E5%8A%A8%E7%9A%84%E5%BC%80%E5%8F%91"><span class="toc-number">1.</span> <span class="toc-text">ZYNQ学习笔记-IIC驱动的开发</span></a><ol class="toc-child"><li class="toc-item toc-level-2"><a class="toc-link" href="#Linux%E4%B8%ADIIC%E8%AE%BE%E5%A4%87%E7%9A%84%E9%87%8D%E8%A6%81%E6%A6%82%E5%BF%B5"><span class="toc-number">1.1.</span> <span class="toc-text">Linux中IIC设备的重要概念</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E4%B8%80%E8%88%AC%E7%9A%84%E9%A9%B1%E5%8A%A8%E6%B3%A8%E5%86%8C%E7%BB%93%E6%9E%84"><span class="toc-number">1.2.</span> <span class="toc-text">一般的驱动注册结构</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E8%AE%BE%E5%A4%87%E5%8C%B9%E9%85%8D%E6%96%B9%E5%BC%8F"><span class="toc-number">1.3.</span> <span class="toc-text">设备匹配方式</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%AE%9E%E9%99%85%E6%95%B0%E6%8D%AE%E4%BC%A0%E8%BE%93%E5%87%BD%E6%95%B0"><span class="toc-number">1.4.</span> <span class="toc-text">实际数据传输函数</span></a></li><li class="toc-item toc-level-2"><a class="toc-link" href="#%E5%AE%9E%E6%88%98-MPU6050%E9%A9%B1%E5%8A%A8%E7%9A%84%E7%BC%96%E5%86%99"><span class="toc-number">1.5.</span> <span class="toc-text">实战-MPU6050驱动的编写</span></a></li></ol></li></ol>
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